Imminent Doom

A combo engine disguised as a damage spell, and the disguise is the constraint that pays for it. The first trigger requires a spell of mana value one, the next a two, then a three, and so on up the curve, each successful payment advancing the doom counter by one. That escalator is the whole strategic axis: the enchantment demands that your deck be assembled as a tight mana-value sequence rather than a pile of efficient cards, and punishes any misstep by stranding the chain at a number you cannot match. Cast a spell whose value does not equal the current counter and the trigger simply does not fire; the counter waits. Notably, it can start earning immediately: enter it with its lone doom counter, then cast any one-mana spell that same turn and it fires for one and steps up to two. What it rewards is not raw card quality but curve discipline, the ability to lay out a turn (or a string of turns) where you can produce exactly a one, then a two, then a three on demand. The payoff scales with the difficulty: by the time you are casting six- and seven-mana spells, the enchantment is throwing six and seven damage for free, having already drained your hand to get there. Red rarely asks you to reorganize a deck around a counting mechanic rather than slot a card into an existing shell; this is one of the few designs that does, and it lives or dies on whether you can build the ladder it demands.